Hello,
Over the turn of the year 2016/17, our L-shaped bungalow was built using sand-lime brick construction. External wall insulation (EWI) was applied, I believe, in November 2016. Inside, gypsum plaster was used, with underfloor heating installed beneath a cement screed. During the last four weeks before moving in (in January 2017), two dehumidifiers were used. The drying progress was said to be good enough that the floor moisture measurement gave the green light for our glued vinyl flooring. We moved in mid-February 2017.
Yesterday, the inspector came. Not without reason. There are condensation issues on an exterior wall in the bedroom and in the utility room. On average, the house has an absolute humidity of 9.5–11.5 g/kg of air. Our inexpensive hygrometers distributed throughout the house showed mostly 55–60% relative humidity in March but have risen noticeably since mid-April, reaching up to 75% in the bedroom. His measurements indicated that this is very likely due to residual construction moisture (the report is still pending). This could also explain why our vinyl flooring has started to lift again *grumble*.
In short: it’s my house, and I want to avoid further problems as quickly as possible. At the moment, I don’t care who is at fault here (whether we should have moved in later or ventilated better… that’s not the point here). So far, we have only aired the house by opening windows for cross-ventilation once a day. I’m not sure yet if twice a day is feasible. That’s why I considered setting up another dehumidifier now in addition to ventilating. Whether it helps, I’ll only find out afterwards. My question is: is it better to use two smaller units (each 10–15 L/day) or one larger one (50 L/day)? It’s also a matter of cost. The smaller ones have the advantage that I can place them distributed around the house but have only a very small condensate tank and have to hope the automatic shutoff works properly. For the large one, I found a model with an integrated condensate pump – it could run continuously. But I suppose proper air circulation in the house would be missing then, right? Does anyone have advice on which option I should choose?
Best regards
PS: I’m not sure about the category placement here in the forum, so please feel free to move this if needed. Thanks
Over the turn of the year 2016/17, our L-shaped bungalow was built using sand-lime brick construction. External wall insulation (EWI) was applied, I believe, in November 2016. Inside, gypsum plaster was used, with underfloor heating installed beneath a cement screed. During the last four weeks before moving in (in January 2017), two dehumidifiers were used. The drying progress was said to be good enough that the floor moisture measurement gave the green light for our glued vinyl flooring. We moved in mid-February 2017.
Yesterday, the inspector came. Not without reason. There are condensation issues on an exterior wall in the bedroom and in the utility room. On average, the house has an absolute humidity of 9.5–11.5 g/kg of air. Our inexpensive hygrometers distributed throughout the house showed mostly 55–60% relative humidity in March but have risen noticeably since mid-April, reaching up to 75% in the bedroom. His measurements indicated that this is very likely due to residual construction moisture (the report is still pending). This could also explain why our vinyl flooring has started to lift again *grumble*.
In short: it’s my house, and I want to avoid further problems as quickly as possible. At the moment, I don’t care who is at fault here (whether we should have moved in later or ventilated better… that’s not the point here). So far, we have only aired the house by opening windows for cross-ventilation once a day. I’m not sure yet if twice a day is feasible. That’s why I considered setting up another dehumidifier now in addition to ventilating. Whether it helps, I’ll only find out afterwards. My question is: is it better to use two smaller units (each 10–15 L/day) or one larger one (50 L/day)? It’s also a matter of cost. The smaller ones have the advantage that I can place them distributed around the house but have only a very small condensate tank and have to hope the automatic shutoff works properly. For the large one, I found a model with an integrated condensate pump – it could run continuously. But I suppose proper air circulation in the house would be missing then, right? Does anyone have advice on which option I should choose?
Best regards
PS: I’m not sure about the category placement here in the forum, so please feel free to move this if needed. Thanks
Don’t you have a mechanical ventilation system with heat recovery?
I think airing only once a day is not enough; even tilting the window open will hardly help.
Based on instinct, I would suggest using two dehumidifiers.
Otherwise, it’s worth mentioning that people used to live for an entire year without any drying measures.
Chin up, fingers crossed, and prepare for repeated costs.
Good luck!
Best regards in short
I think airing only once a day is not enough; even tilting the window open will hardly help.
Based on instinct, I would suggest using two dehumidifiers.
Otherwise, it’s worth mentioning that people used to live for an entire year without any drying measures.
Chin up, fingers crossed, and prepare for repeated costs.
Good luck!
Best regards in short
B
Bieber08155 May 2017 15:35rabudde schrieb:
Our inexpensive hygrometers distributed throughout the house mostly showed 55-60% relative humidity in March, but since mid-April they have risen significantly, reaching up to 75% in the bedroom. How warm do you keep it? Before setting up dehumidifiers, you should make sure that heating and ventilation have been fully utilized. You should manage to do cross-ventilation through the whole house twice a day (morning and evening), keeping it nicely heated in between.
No, we consciously decided against a mechanical ventilation system with heat recovery, as we know about it from friends.
The rooms are kept between 22-23°C (72-73°F), except for the bedrooms (18-19°C / 64-66°F) and the technical room, where it is 20-21°C (68-70°F). However, I cannot heat arbitrarily high, because with a supply temperature of ≥28°C (82°F), the vinyl flooring will probably be damaged.
The presumably present humidity likely causes significant condensation at the drinking water connection (inlet temperature approx. 4°C / 39°F) and on the brine pipes of the deep geothermal drilling (even though these are already insulated). So much condensation accumulates that it creates actual puddles. I think especially in the area of the technical room, a dehumidifier will initially be necessary.
What I actually forgot to mention as the main background: the surveyor said yesterday that this trapped moisture can take 3-4 years to fully dry out – I also heard something similar somewhere during the construction phase but had pushed it out of my mind. My question again: can using construction dryers shorten this drying time? Specifically, if a dryer runs all day and could reduce the indoor humidity to around 40% during the day, would that accelerate the drying of the plastered masonry?
The rooms are kept between 22-23°C (72-73°F), except for the bedrooms (18-19°C / 64-66°F) and the technical room, where it is 20-21°C (68-70°F). However, I cannot heat arbitrarily high, because with a supply temperature of ≥28°C (82°F), the vinyl flooring will probably be damaged.
The presumably present humidity likely causes significant condensation at the drinking water connection (inlet temperature approx. 4°C / 39°F) and on the brine pipes of the deep geothermal drilling (even though these are already insulated). So much condensation accumulates that it creates actual puddles. I think especially in the area of the technical room, a dehumidifier will initially be necessary.
What I actually forgot to mention as the main background: the surveyor said yesterday that this trapped moisture can take 3-4 years to fully dry out – I also heard something similar somewhere during the construction phase but had pushed it out of my mind. My question again: can using construction dryers shorten this drying time? Specifically, if a dryer runs all day and could reduce the indoor humidity to around 40% during the day, would that accelerate the drying of the plastered masonry?
Condensation at 70% humidity, uninsulated connections, etc. To me, this sounds more like construction defects than user-related issues. How was the regular air exchange verified in your case? If you do not have a mechanical ventilation system, the air exchange must work differently—simply opening windows is not an acceptable solution here.
Hi,
It doesn't necessarily have to be a construction defect. Ventilating once a day in a new build is FAR too little. Less than three times daily really won't do!
Uninsulated connections can also include things like a water meter. Ours isn’t insulated either, and at first, there was dripping there as well.
To the original poster:
We used different dehumidifiers.
Trotec TTK 105 S, TTK 140 S, and TTK 170 S. The smaller 105 is already quite good, but the larger ones extract significantly more water from the air. When considering dehumidification efficiency, they also consume noticeably less electricity. The 140 models use the same power as the 105 but remove more water. The 170 uses about 50% more electricity than the 105 but easily extracted twice as much water for us.
So better one large unit than two small ones. They’re all loud.
Regards,
Andreas
77.willo schrieb:
Condensation at 70% humidity, uninsulated connections, etc. To me, this sounds more like construction defects than usage problems.
It doesn't necessarily have to be a construction defect. Ventilating once a day in a new build is FAR too little. Less than three times daily really won't do!
Uninsulated connections can also include things like a water meter. Ours isn’t insulated either, and at first, there was dripping there as well.
To the original poster:
We used different dehumidifiers.
Trotec TTK 105 S, TTK 140 S, and TTK 170 S. The smaller 105 is already quite good, but the larger ones extract significantly more water from the air. When considering dehumidification efficiency, they also consume noticeably less electricity. The 140 models use the same power as the 105 but remove more water. The 170 uses about 50% more electricity than the 105 but easily extracted twice as much water for us.
So better one large unit than two small ones. They’re all loud.
Regards,
Andreas
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